1. Field of the Invention
The present invention is directed to a vibration damping device including a base body rotatable about an axis of rotation and a deflection mass arrangement arranged in the base body, the deflection mass arrangement having at least one deflection mass and a deflection path associated with the at least one deflection mass and along which the deflection mass is movable during rotation of the base body about the axis of rotation, wherein the deflection path has a vertex area and deflection areas on both sides of the vertex area the deflection areas have a decreasing distance from the axis of rotation proceeding from the vertex area toward their end areas.
2. Description of the Related Art
A vibration damping device is disclosed in DE 44 26 317 A1 having a base body with a deflection mass arrangement including deflection masses arranged in deflection paths having vertex areas and deflection area. This reference further discloses disklike deflection masses distributed about the axis of rotation of the base body in a plurality of receiving chambers curving around the axis of rotation. The deflection masses roll along an outer circumferential wall of the receiving chambers. This type of damping device is referred to as a speed-adaptive damper, wherein the deflection masses are positioned in the vertex area of the respective deflection path at the greatest distance radially from the axis of rotation when the base body is rotating at a uniform rate. Irregularities in the rotational movement cause a deflection of the deflection masses out of the vertex areas. As the deflection masses move from the vertex area, the curvature of the deflection paths forces the deflection masses to approach the axis of rotation and, thereby displace centrifugal potential of the deflection masses. This movement of the deflection masses damps torsional vibrations, especially periodic torsional vibrations. The deflection arrangement may be designed with a particular curvature of the deflection paths and a particular weight of the deflection masses to adapt the deflection arrangement, for example, to higher harmonic orders of the vibrational excitation generated by an internal combustion engine.
When the occurring excitations lead to relatively large deflections of the individual deflection masses, the latter reach as far as the respective end areas of the deflection paths. Since the deflection paths have only a limited circumferential extension, the deflection masses may knock against the end areas of the deflection paths when deflection amplitudes are too great. This abrupt collision may manifest itself by rattling noises or in further vibrational excitation. This impairs driving comfort as well as the behavior for minimizing vibrational excitations generated in an existing drive system.
It is the object of the present invention to provide a vibration damping device in which the damping behavior is improved, especially during large vibrational excitations.
According to an embodiment of the present invention, the object is met by a vibration damping device comprising a base body operatively arranged for rotating about an axis of rotation and a deflection mass arrangement arranged in the base body. The deflection mass arrangement has at least one deflection mass and a deflection path associated with the at least one deflection mass so that the at least one deflection mass is movable along the deflection mass during rotation of the base body about the axis of rotation. The deflection path has a vertex area and deflection areas on both sides of the vertex area. The deflection areas have end areas and are arranged so that a distance of the deflection area from the axis of rotation decreases as the deflection area proceeds from the vertex area toward the end areas.
The vibration damping device according to the present invention also comprises a braking arrangement which acts in the end areas of the deflection areas by gradually slowing the movement of the at least one deflection mass when the at least one deflection mass approaches or reaches a respective end area of the deflection path.
The vibration damping device according to the invention prevents the knocking of a deflection mass and the generation of a vibrational excitation by braking the deflection masses through a gradual slowing down of movement.
The braking arrangement may comprise a stop device which is displaceable at least within an area of displacement by the at least one deflection mass against the action of a force. An additional damping moment resulting from the displacement of the stop device against the influence of force, which displacement becomes necessary in a compulsory manner, is introduced in this way.
The stop device may comprise a stop area associated with each of the two end areas of a deflection path.
In this case, it is advantageous when the stop device is movable in different directions by at least one deflection mass when the at least one deflection mass strikes the different stop areas. Accordingly, the stop device may be moved back and forth alternately by the deflection mass or deflection masses depending on the movement direction.
This movement of the stop device may optionally be generated, for example, against the action of a friction force. Moreover, the movement may occur against the action of a restoring spring arrangement.
An embodiment having a simple construction may be achieved when the stop device is elastically deformable at its stop areas. The stop areas may, for example, comprise stop webs proceeding from a main body.
In another embodiment, which may be combined with the possible embodiments discussed above, the braking arrangement may comprise a portion having increased elasticity in the end areas of the deflection areas. In addition, or alternatively, the end areas of the deflection area may comprise a portion with increased rolling or sliding movement resistance. The undesirable colliding of a deflection body in the end areas of its movement may also be prevented by arranging an axially projecting guide pin on the at least one deflection body which moves along at least one guide path during the movement of the at least one deflection body along the deflection path. Furthermore, the guide path is elastically deformable at least in its respective end portions in which the at least one guide pin is located when the at least one deflection mass is positioned in the end areas of the deflection area. Furthermore, the associated guide pin may also be elastically deformable.
As discussed above, the problem of the prior art in which the deflection masses collide at structural component groups terminating the movement path of the deflection masses occurs when there is a relatively strong vibrational excitation which leads to correspondingly large deflections. Accordingly, a further possibility provided by the present invention for improving the damping behavior by preventing a collision at path ends is directed toward enlarging the movement area of the individual deflection masses while retaining the same constructional volume. Therefore, a further embodiment of the present invention includes a vibration damping device for a drive system of a motor vehicle comprising a deflection mass arrangement arranged in a base body which is rotatable about an axis of rotation. The deflection mass arrangement has at least two deflection masses and a deflection path which is associated with each of the deflection masses and along which the deflection masses can move during rotation of the base body about the axis of rotation. The deflection path has a vertex area and deflection areas on both sides of the vertex area. The deflection areas have end areas and are arranged so that a distance of the deflection area from the axis of rotation decreases as the deflection area proceeds from the vertex area toward the end areas. The at least two deflection paths adjoin one another in respective adjacent end areas and an overlapping volume is formed in the area of the adjoining end. Each of the deflection masses associated with the two adjoining deflection paths projects into the overlapping volume when it is positioned in the respective end area of the deflection path associated with it.
The above arrangement ensures that there is a volume area in which different deflection masses may engage depending on the vibrational deflection. However, since each of the deflection masses move in phase, i.e., in the same circumferential direction, the state in which both deflection masses of directly adjacent deflection paths attempt to enter simultaneously into the overlapping volume area does not occur. Accordingly, the available volume may be used in an overlapping manner by a plurality of deflection masses, thereby allowing the movement paths to be lengthened. The increased length of the movement path may be used to reduce the risk of striking against end areas of the deflection path or increase the quantity of oscillating masses.
For example, two directly adjacent deflection paths may essentially run into one another in a wedge-shaped manner in their end areas which adjoin one another.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.